I truly understand how you feel. I also failed the NCLEX-RN when I took it.
I waited about 30 days after I graduated to take my exam, Some people in my class only waited a week and they passed with the minimum amount of questions (they were extremely smart and I was happy for them that they had passed).
I took ALL the questions and that took me little over 3 hours to complete. I had a gut feeling that I failed it and when I got the NCLEX letter, I was not surprised. It still hurt bad. I did ALL the Kaplan Tests and quizzes and readiness tests. I sat everyday for hours on end at the kitchen table. I did feel like a failure.
I do like Kaplan and how they taught to avoid some pitfalls e.g. Dont answer with "Why". And I still have never asked my patient "why" in any of my questions / nursing practice because I truly believe in the rational Kaplan provides. I believe I failed, because I was trying to use a brute force method of answering as many questions as possible to learn the test. That strategy might work for some, but it failed me.
Everybody is going to be different on what works for them. What worked for me is changing my approach on how I study and where I study. I mostly Saunders as my study resource, made my own quizzes via quizlet from the Saunders material, and took practice exams / quizzes at my local library. My local library has computers where you can reserve a computer, so I had to get up in the morning and drive and took a practice exam / quizzes there. I tried to make it realistic as if I was actually driving to take the NCLEX (because I have really bad test anxiety) and get out of my comfort zone of the kitchen table. I had to understand that the NCLEX-RN is a safety exam and that they want to know that you will practice safely as a nurse. I did not use the brute force method of taking as many questions as possible to solely rely on, I did not use Kaplan as nearly as much because I had already done it. I have not tried UWorld or any other except for Saunders.
The advice I got from my nursing instructors after I failed the NCLEX-RN, schedule to take it as soon as possible and believe. I made my 2nd attempt 45 days later and took 75 questions. I felt nervously OK when my test ended. I didn't feel like celebrating or telling anyone that I only took 75 questions, I did not want to talk to anyone at all - It was a hold my breath until I got my results sort of deal. I did not use the whole credit-card retry attempt to see if I had passed. I just waited for my results.
My advice, is similar, schedule to take it as soon as possible, put your social life on complete and utter hold (even if that means no more boyfriend for a month or two), believe that this exam will be harder than any other exam in your entire life, but most important, trust and believe in yourself.